Tailored Polyurethane Synthesis from AB-Type Monomers

Inspired by precisely designed protein synthesis from amino acids, we demonstrate precise polyurethane synthesis from novel AB-type monomers exhibiting side chain functionalities to implement an elaborate molecular/material design, which has been difficult to address by a conventional method. To realize this idea, we designed acylazide precursor monomers having alcohol moieties, which can transform into actual AB-type monomer species having isocyanate and alcohol groups by Curtius rearrangement. Polymers from the monomers afforded self-standing films that showed very different mechanical properties from conventional polyurethanes. The detailed kinetic analysis of the Curtius rearrangement and (co)polymerization studies revealed that the polyurethane backbone structure could be flexibly programmed by the choice or combination of monomers. Moreover, the resulting polymers were further functionalized by postpolymerization modification, enabling fine-tuning of their properties. Overall, the utility of this AB-type monomer protocol to implement tailored polyurethane synthesis is thoroughly studied.